The prior art also embraces cooking apparatus (see French Patent 1,578,666 and French Patent no. 2,324,269) which dry-cook the food products.
The first of the above patents refers to an apparatus comprising, internally to the thermoventilated cooking chamber, a perforated cylindrical container, rotating about a horizontal axis and having a single opening for the loading and the unloading of the food products, which opening is accessible to the operator frontally through a vertical hatch arranged on a wall of the container.
In the second above patent document, the apparatus comprises a container, substantially cylindrical and having two distinct openings: one frontal and destined to be used for the loading of the food to be cooked, accessible through the hatch of the chamber, the other made on the lateral surface of the container, having the purpose of allowing the cooked food to be unloaded, on to an underlying drawer, by means of inversion in the rotation direction of the container.
The above-mentioned cooking apparatus, independently of their operative principles, are characterised by numerous drawbacks.
A first, common drawback, both in the apparatus envisaging immersion of the products and in the apparatus operating drily, in which however the food products are still coated with oil, is constituted by the fact that the food products are substantially coated with the cooking oil and can be indigestible and damaging for the health of the consumers if the cooking temperature falls for any reason whatsoever below a prefixed limit value, which value is characteristic for each food product (for example the said limit for chipped potatoes is about 190 degrees C.
A further drawback of the machines operating by immersion is constituted by the fact that the oil in the oil bath is repeatedly re-used, apart from the normal additions made for oil lost, so that after a certain operative time the oil tends to degrade, with the formation of toxic substances that, even in the best of cases, determines a fall in the organic characteristics of the cooked products. Also, the consumer of the food cannot perform any check on the healthiness of the products which he or she is eating, and has to trust in the good practices of the operative who is charged with the regular substitution of the entire contents of the oil bath of the apparatus.
The machines operating by immersion are also negatively characterised by a considerable inertia when they are first activated.
The necessity to constantly maintain the optimal temperature, as above-mentioned, is particularly critical in the apparatus which dry-cook, made according to the teachings provided in the above-mentioned documents.
Indeed, in the said apparatus, each time that the hatch of the thermo-ventilated chamber is opened in order to introduce a new quantity of food into the container, the air which is inside the container exits at a high temperature and strikes the operator, causing an unpleasant and even dangerous experience for the operator, who must guard against burns because of the said high temperature.
This rush of exiting air, furthermore, causes a disadvantageous lowering of the internal temperature of the chamber, which falls below the optimal value and causes an increase in cooking times and a loss of energy in the apparatus.
A further characteristic drawback existing in the apparatus of U.S. Pat. No. 2,324,209 is represented movement preliminary to unloading, the cooked products are subjected to a jolt consequent to the sudden variation in the curvature of the walls.
The jolt causes in all cases a certain deterioration in the product and, in the case of crispy or frail foods, is the cause of a considerable amount of waste due to the breaking of the products.